Given that, following Twitlight (sic), Vampires and Werefolk seem to have been subsumed into "Urban Fantasy", I think that "SF Horror" has descended to occasional film novelisations like Alien and Species.

If you just want SF with horrific elements, you could try Charles Stross' Laundry series, startting with "The Atrocity Archives".

Imagine being stuck in a spaceship for many months, but you have to live in your spacesuit with only a few days of air because the air system in the spaceship is contaminated with a spore that will very slowly kill you by rotting your lungs.

I think this was in a Brian Stableford story, but cannot remember which. However, he often comes up with some very black horrors to twist the mind.